Method and apparatus for increasing the lift of airplanes



May 5, 1931. I T BER CK 1,804,307

METHOD AND APPARATUS FOR INCREASING THE LIFT OF AIRPLANBS Filed June 25,1930 gwuento c Patented May 5, 1931 UNI STATES.

PATENT OFFICE.

rm IBERIBECK, .OF BALTIMO BE, MARYLAND mt'rnon m APPARATUS ron moanasme'rirr: mm or Amman-Es Application filed June 25,

This invention relates to improvements in airplanes and moreparticularly has reference to a method and means for increasing the liftfactor of airplanes.

A considerable effort has been expended to, increase the lift efi'ectonairplane wings, as its desirability has long been recognized. At thepresent, the advantage to be gained from a short distance take-off and arelatively low landing speed, so that the plane may land in small spacesare still bein sought. Methods proposed to secure these a vantages havebeen an increased wing camber and an increased wing area. However, theseexpeclients are limited by the size of the wings which are capable ofbeing used. Other methods have proposed a wing construction whichallowsthe camber and the wing area I to be altered at will.; Whilethislatter type of construction is correct in theory, it is neverthelessimpractical because of the many mechanical parts required by it.

Besides these practices mentioned above, attempts have been made toincrease the lifting power of anairfoil by increasing the aircurrentvelocity over the top surface. Along these lines the slotted winghas had considerable succes but as yet it is not suitable in vallinstances. Also among this latter type of methods for increasing thelift of airfoils, is the use of blowers adapted to direct a stream .ofair over the upper surface of the plane. These have been unsuccessfuldue to the fact that a small increase of velocity is obtained for thegreat amount ofweight added to the plane. It is the major object of thisinvention to provide a method for increasing the lift of airplanes andmeans for carrying the same into effect which lack the inherent defectsof methods and constructions now in present practice.

An equally important object of the invention is the provision ofa-method and means for increasing the lift of airfoils independently ofthe airfoils themselves. Q,

Anotherobject of the invention is the provision of a method forincreasing the lift of an airplane comprising revolving a sustain- 1930.Serial No. 463,802.

blade elements having an airfoil section, the

blade elements adapted to be rotated about a horizontal axis.

Yet another objectof the invention is the W provision of a plurality ofgroups of sustainmg surfaces or impellers adapted to be mounted upon theupper surface of a wing of an airplane on each side of the fuselage, or

other parts of the plane, each of the impellers being provided with aplurality of blade elements having an airfoil section, and meansmounted'upon the airplane, with which the impellers are associated, forrotatingthem about a horizontal axis so as to increase the lift factorof the completed plane.

A further object of the invention is the designing of an impellercomprising a hub adapted to be mounted upon a rotatable shaft, aplurality of blade elements of an airfoil section being positioned uponthe hub.

Still a further object of the invention is the designing of an impelleradapted to be rc tated about a horizontal a'xis and positioned upontheupper surface of a wing of an airplane, theimpeller comprising a hubwith a plurality of blade elements of an airfoil section positionedthereon, the impeller being fixed upon a rotating shaft which extendsthrough the hub and has its outer end secured to the tips of the bladeelements.

With these and other objects in view which may be incident to myimprovements, the invention consists in the method and means forcarryingthe same into effect to be hereinafter 9 set forth and claimed,with the understanding that the necessary steps and the constructionsdisclosed for carrying them out may be varied without departing from thespirit of the invention or the scope of the appended claims.

The present invention comprehends the provision of a method andapparatus for increasing the lift factor of planes. One man- 'ner ofpractically effecting the concept of the invention is the provision of aplurality of impellers adapted to be mounted upon the wing of anairplane or other positions thereon, each of the impellers comprising aplurality of blade elements having an airfoil section. The inventionalso conun'ehends the rotation of these sustaining surfaces about ahorizontal axis so as to increase the lift factor of the airfoilindependently of the airfoil itself.

In order to make my invention more clearly understood, I have shown inthe accompanying drawings, means for carrying the same into practicaleffect without limiting the improvements in their useful applications tothe particular constructions, which, for the purpose of explanation,have been made the sub- ]ect ofill'ustration.

' In the-drawings:

Figure 1 is a front elevational view of an airplane having the impellersforming the subject matter of the invention associated therewith.

Figure 2 is a vertical sectional view along the line 2-2 of Figure 1,and shows a group of blade elements forming each impeller.

Figure 3 is a vertical sectional view on the line 3-3 of Figure 1looking towards the hub of the impeller.

' Figure 4 is a longitudinal vertical sectional view showing in detailone of the impellers with its blade elements.

Figure 5 is a perspective view of one of the blade elements of theimpeller.

Figure 6 is an end view of an impeller lookin towards the hub thereof,and shows a di erent type of mounting for the impellers.

Throughout the drawings similar reference numerals refer tolike parts inthe different views. There is shown in Figure 1 an airplane'having awing 1, fuselage 2, and a landing gear wing 3. As may be observed,suitable struts 4 are employed for bracing the wing. The fuselage hasmounted thereon the usual power source ormotor 5 provided with apropeller 6.

Adapted to be mounted on the upper sur-, face of the wing 1 are aplurality of impellers or groups of rotatable sustaining surfaces,generally designated by the numeral 7, which form the subject matter ofthis invention. Each impeller is formed of a plurality of metal bladeelements 8 which are secured to a metallic hub 9, in any suitablemanner. I' have found, however, that the construction disclosed inFigure 4 for secur- 'ing the blade elements to the hub, will producevery satisfactory and efiicient results.

The hub 9 is. in effect, a hollow cylinder closed at one end by a base.On its inner surface the hub is provided with a flange 10 which extendsentirely around the hub and .is'adapted to cooperate with a groove 11,

.formed in the base section 12 of each blade ing flange 14 which has atapere element 8. As may be observed, the base 12 of each blade elementis a section of a hollow cylinder, and when positioned as shown inFigure 4. its upper surface is adapted to fit flush with the innersurface of the hub.

In order to maintain the blade elements in position a cylindrical keeper13 is employed. The outer diameter of this keeper is such that when itis placed within the hub, its outer surface will be in bearing with theinner surface of the bases of the blade elements, and will maintain theblade elements in position.

Of course. the keeper 13 may be maintained in the posit-ion shown inFigure 4 in any number of ways, such as by welding, by means of boltspassing through the hub, each blade element and the keeper itself. or bysuitable keys and keyways therefor. These latter practices have theadvantage that the blade elements are detachable. However. any of thesemeans, as well as others not mentioned, may be employed for maintainingthe keeper in position, without departing from the spirit of theinvention or the scope of the appended claims.

It should be noted that the hub is provided at its center with aninwardl projectpassageway adapted to receive the tapered end of a shaft15 which is securely. locked therein by means of a key, not shown. andthe nut 16 threaded on the end of the shaft so as to pre- I vent therotation of the shaft with respect to the impeller hub. However, othermeans than those disclosed may be employed for securing the hub to theshaft without exceeding the spirit of the invention.

It has been previously pointed out that the impellers are mounted uponthe upper surface of the wing. In order to accomplish this, suitablebearing mounts 17 are positioned upon the upper surface of the wing andthey are adapted to support the shaft 15 of each impeller. The free endof the shaft 15 extends within the housing 18 in which may be mounted asuitable power source for driving the impellers. Housing 18 is suit-.abl stream lined so as to reduce the parasitic not be followed however,as the power source can be positioned within the fuselage of the planeor the impellers may be driven through gearing or other powertransmitting mechanism by means of the motor driving the propeller 6. Asthe invention is not dependent upon the position of the power sourceadapted to drive the impellers, it has not been shown in theaccompanying drawings, in order to simplify them as much as possible.Each shaft 15 may be directly connected'to its power source, or it maybe com nected thereto through means of either high 'or low speedgearing. Also, if desired, a suitable clutch may be positioned betweenthe power source and each shaft 15 so that either or both impellers maybe operated at will.

In some instances it may be found desirable to continue the shaft 15through the hub and outwardly towards the ends of the blade elements.When such a construction is employed a spider 19, shown in Figure 6, maybe connected to the shaft and to the blade elements. This type ofconstruction is desirable where the blade elements possess considerablelength, as it affords a support for them near their tips. I

The hub, blade elements, and keeper are preferably made of metallicconstruction.

Any suitable metal possessing the required compressive and-tensilestrength factors as well as a light weight or low density, is satisfactory. Another condition'desirable in the metal forming the impelleris that it be unaffected by corrosion due to atmospheric and weatherconditions. Suitable aluminum alloys fulfill all the conditions setforth above, although any other type of metal now employed in theconstruction of airplane propellers may be used.

As hereinbefore described, each of the blade elements possess an airfoilsection from a point where it joins its base to its tip. The bladeelements maybe constructed in accordance with any of the well-knownprac- 'tices for forming'the blades of metal propellers'.

'ments are tapered as to thickness.

If desired, each impeller maybe formed of a single piece of material.For instance a hollow cylinder which is formed of the desired metal maybe machined to form the blades andhub and after the elements have beencut to shape'they may be buffed and burnished so as to present a smoothsurface ofthe desired form. i

' It has been mentioned that the blade ele- It may also be observed thattheir planforin, as shown in Figure 5', is also tapered. The airfoilsection employed is preferably ,that

shown in Figure 2, where an airfoil section having a concave lowersurface is disclosed By this construction-the median line of eachairfoil section is substantially that of a circular arc. In either ofthe constructions shown in Figures 3 and 6, the blade elements arepositioned'with respect to their hub so that there is a space 20 leftbetween the leading and trailing edges ofthe adjacent sustainingsurfaces. Because of the tapered planform givento each rotatingsustaining surface,'it may be noted that the spaces 20 between ad acentblade elements, is increased towards the tips of the elements.

factors.

Also to be noted is the fact that the blade elements of each impellerare so arranged that the under-surface of each element forms thecircumference of a circle having its center at the center of the hub,while theleading edge of any blade element is next to the trailing edgeof an adjacent blade'element. This arrangement is clearly shown in bothFigures 3 and 6. As illustrated in the drawings, blades 8 are so pitchedthat the leading edge of one blade is spaced from the shaft a distancegreater than the trailing edge. This construction permits the leadingedge of each block'to be acted upon by the air stream.

It'has been pointed out as an' object of the invention to provide amethod and means for increasing the lifting power of airplanes, thisincreased lift being of particular advantage in allowing a shortdistance takeoff and. a relatively low landing speed and small space forlanding a plane. As is well known, the creation of lift in an airfoil isdue to the pressure differential existing between the pressure upon theupper surface of the airfoil and the pressure uponits lower sur-, face.The pressure upon the upper surface is negative in value, or a suctioneffect, while that upon the lower surface is positive with respect tothe atmospheric pressure. Application of some of the theorems ofhydrodynamics, particularly Bernoullis, are employed to explain thevalues of these areas of high and low pressure abouttheairfoil. Dividingthe resultant of the force on the airfoil, created by the pressuredifferential just mentioned, into its components, there isobtained alift force and a drag force. The value of the lift as well as the dragforce changes for various angles of the airfdtl with respect to therelative wind or for changes in t7 3 angle of attack.

This theory, given above in connection with airfoils functioning aswings for an airplane-.isnowaccepted as an explanation forthe-"operation of a propeller or air screw. In the propeller -.theblades thereof are formed of a plurality. of airfoil sections whichrotate in a vertical plane at a high velocity.

With the propeller, however, the lift force is in a horizontal plane andis parallel to the axis ,of rotation of the propeller, while (he drag isalso in a horizontal plane but is perpendicular to the axis. In apropeller, of course, the lift is called the thrust and it is this forcethat causes the airplane to be moved forwardly in a horizontaldirection.

.that of a plurality of airfoils,-that its thrust is dependent upon aconsiderable number of One of the most important factors -is the bladevelocity which determines to a considerable extent, the velocity of theair currents and air stream passing over the airfoils comprising theblades of the propeller.

while the blades of a propeller are rotated in a vertical plane.

Whatever may be the theory of operation of the impellers, it is thepurpose of this invention to combine the operating principles of a wingand those of a propeller so that the best features of both'of thesedevices are obtained with the result that when the impellers areactuated a lift independent of the wing of the plane is created.

In Figure 2 an impeller is shown rotating in a counterclockwisedirection with the relative wind directed towards the right as indicatedby the arrows. When the blade elements of Figure 2 are in the positionshown, air currents will enter the interior of the impeller due to theopening 20 between the leading and trailing edges of adjacent bladeelements.

I Upon entering the opening or space 20, the air is suddenly restrictedso that an in crease in velocity results. Immediately upon passingthrough the passageway, and entering'into the'impeller so that it isadjacent the under-surface of the blade elements, the

-velocity is reduced due to the release of the air from its confinementby the passage between the blade elements through which it passes. Theresult of the reduction of velocity of the air stream passing throughthe impeller causes an increase 1n its ressure WhICh creates a pressuredifferential etween the outer and inner surfaces of the blade elements.The air stream encircled by the "impeller blades, having entered at theleft, passes outwardly from the interior of the impeller in a path ofleast resistance.

The impellers are rotated at a considerable speed and consequently. eachblade element attains a high velocity. Each blade element,

therefore, rotates a great many times for any given period, taken as aunit, and the resultant lift of the impeller will remain substantiallyconstant. The impellers are rotated at any suitable speed which itdetermined by'the conditions which must be met.

When it is desired to take ofi, the motor 5 is actuated so as to rotatethe propeller 6,

tained as desired. When it is desired to land the plane, the impellersare rotated so as to obtain their lift, and the plane is landed in theusual manner but with the advantage that a decrease in area required toland it is obtained.

The impellers may or may not be actuated while the ship is flying.Because of the increased lift obtained by them they are of considerableadvantage in obtaining altitude and in climbing. As the impellers may beassociated with any type of plane bi merely mounting them upon a wing orot er part of the plane, it is apparent that they will increase theceiling which the ship may obtain.

It is also apparent that the impellers may be utilized for stabilizingan airplane with which they are associated and are of considerablebenefit in pulling the airplane out of spins, rolls, or dives, as themay either be actuated together or indepen ently.

, It has been found by experiment that when a device constructed inaccordance with the present invention is placed in operation, that thereis produced a movement in a horizontal direction as well as the lifteffect hereinbefore described. For instance, when a structure isprovided with the rotary impellers, there is a decided force exerted ina horizontal direction which is effected for producing movement in ahorizontal direction. Thus, it is possible that impellers constructed inaccordance with the present invention may be employed for moving anairplane equipped with the same in a horizontal direction as well astending to increase the lift. It, of course, is obvious that theimpellers may be arranged in positions other than thatshown in thedrawings to obtain thefull benefit. of the force produce in thehorizontal plane by the im ellers.

ile each impeller has been shown. as composed of three blade elements,it is obvious thatmore may-be employed, if desired. In connection withthe length and the width of each'blade element, or its aspect ratio, itmay be observed that this may be varied at will, and is determined bythe articular re sults sought to be attained. imilarly the thickness ofthe airfoil section or its maximum ordinate is determined by thespecialconditions which the impellersare required to meet. By the use of thespider construction shown in Figure 6, the length of the blade elementsand consequently the area, may lie increased. If desired, the shaft 15may extend beyond the tips of each blade element and its outer end maybe supported upon an upright bearing similar to that designated by thereference numeralv17.

Although the blade elements have been dis closed as associated witha-monoplane, it is to be understood that, the invention is in nowayslimited to thatrtype of airship. Ob-

viously, the impellers could be associated with a multi-wing plane, andcould be positioned upon each wing or upon the upper wing only. In allinstances, wherever the impellers are employed, they are positioned atsuch a distance from a wing (or wings in the case of a multi-wing plane)that they do not interfere with the air currents passing adjacent thewing. Of course, in any instance theblades are so arranged relative tothe rotation of the impeller and the direction of movementof the airstream as to exert a desirable effect.

It may be found advantageous to'construct the impeller blades so thatthe assembled impeller is of a larger diameter at the blade tips than atthe hub.

Having described the features and operation of the device, it will beappreciated from the foregoing description that I have provided a methodand means for greatly increasing the lifting powers of airfoils. Suchconstruction as that disclosed will allow a short distance take off fora plane and a relatively small landing area besides having many otheradvantageous effects which re sult from the benefit of increasing thelift of airfoils.

\Vhile I have shown and described the preferred embodiment of myinvention, I wish it to be understood that 1 do not confine my self tothe precise means herein set forth for performing the method outlinedabove, as it is apparent that many changes and variations may be madetherein, by those skilled in the art, without departing from the spiritof the invention or exceeding the scope of the appended claims.

I claim:

1. An impeller for an airplane adapted to be associated with a wingthereof, said impeller comprising a hub havin a plurality of bladeelements having an air oil section positioned thereon in substantiallycylindrical formation, the leading edge of one blade being closelypositioned with respect to the trailing edge of an adjacent blade so asto form a restricted opening between adjacent blades, the leading edgesof the blades being positioned a greater distance from the axis of thecylinder formed by the blades than the trailing edges, said bladeelements adapted 'to be rotated about a horizontal axis.

2. An impeller adapted to be associated with a wing of an airplane forincreasing the lift of said plane, said impeller comprising acylindrical hub closed at one end, a pluralityof blade elements havingbase portions adapted to sit flush within said hub, and a keeperpositioned within said hub for maintaining the blade elements on thehub, said hub being mounted upon a shaft adapted to be rotated.

3. An impeller adapted to be associated with a wing'of an airplane forincreasing the lift of said plane, said impeller comprising acylindrical hub closed at one end, a plurality of blade elementsof anairfoil section having base portions adapted to sit flush with said hub,and a keeper'positioned concentrically within said hub for maintainingthe blade elements on the hub, said hub being mounted upon a shaftadapted to be rotated.

l. An impeller adapted to increase the lift of an airplane, saidimpeller comprising a hollow cylindrical hub havinga closed end, acircular flange formed within said hub, blade elements havingsemi-annular base portions positioned within said hub, the base of eachblade element being provided with a groove adapted to cooperate withsaid flange, and a keeper member positioned withblade elements formaintaining the blade elements in position, said impeller adapted to bemounted upon the uppersurface of the wing of the airplane and to berotated about a horizontal axis.

5. An impeller adapted to increase the lift of an airplane, saidimpeller comprising a hollow cylindrical hub having a closed end, acircular flange formed withinsaid hub, blade elements having an airfoilsection positioned within said hub, the base of each blade element beingprovided with a groove adapted to cooperate with saidflange, and akeeper member positioned concentrically within the assembled bladeelements for maintaining the blade elements in position, said impelleradapted to be mounted upon the upper surface of the wing of the airplaneand to be rotated about a horizontal axis.

6. An impeller adapted to be associated with an airplane for increasingthe lift thereof, said impeller comprising a hub, a plurality of bladeelements secured thereto in substantially cylindrical formation, theleading edge of one blade being closely positioned with respect to thetrailing edge of an adjacent blade so as to form a restricted openingbetween adjacent blades, the leading ethos of the blades beingpositioned a greater distance from the axisof the cylinder formed -inthe annulus formed by the assembled by the blades than the trailingedges, each of said blade elements having an airfoil section and formedwith a tapered plani'orm, said blade elements adapted to be rotatedabout a horizontal axis.

. 7. .kn impeller for an. airplane adapted to increase the lift thereof,said impeller comprisinga cylindrical-like hub havinga closed end, aplurality of blade elements having an airfoil section mounted uponsaidhub in spaced apart relationship with respect to each 8. In anairplane; an impeller mounted upon each semi-span of a wing, each ofsaid impellers comprising a hub and a plurality of fixed blade elementsassociated therewith, 5 said. blade elements being so positioned as toform a substantially cylindrical surface, said hub beingmounted upon arotatable shaft perpendicular to the uselage of the plane, and means forrotating said shaft so as to actuate the impellers, said blades alsobeing positioned so that the leading edges thereof. are positioned fromtheaxis of the cylinder a greaterdistance than the trailing edgesthereof. 15 9. In an airplane having an impeller mounted uponeachsemi-span of a wing, each of said impellers comprising a single hub, aplurality of blade elements having an airfoil section-positioned uponsaid hub in spaced Q apart relationship with respect to each other in,cylindrical formation, the leading and trailing edges of two adjacentblade elements being adjacent each other so as to form a restrictedopening between adjacent blades,

5" the hub of each impeller being mounted upon a rotatable shaftparallel with the longitudi: nal axis. of the wing and perpendicular tothe transverse axis of the wing, and means for rotating said impeller.

:0 10;v An apparatus for propelling and increasing the lift of anairplane comprising an impeller mounted upon each semi-span of a wing,each ofsaid impellers comprising a I hub and a plurality of fixed bladeelements '86 associated therewith in substantially cylindricalformation, the leading edge of one blade being closely positioned withrespect to the trailing edge of an adjacent blade so as'to forma'restricted openingbetween adjacent blades, the leading edges of theblades being positioned a greater distance from the axis of the cylinderformed b the blades than the trailing edges, said hub being mounted 11on a rotatable shaft perpendicularto 5 the uselage of the plane, andmeans for rotating said shaft so as to actuate the impellers.

11. An'airplane consisting of a body portion, a wing structureassociated therewith, in means for propelling the airplane through theair, means mounted on each semi-span of the wing comprising an impelleradapted to increase the lift thereof, said impeller comprising acylindrical-like hub having ,a closed 65 end, a plurality of bladeelements having an airfoil section mounted upon said hub in spaced apartrelationship with respect to each other, said elements being sopositioned that the leading and trailing edges of any two of 00 them areadjacent each other, said hub adapted to be mounted upon a rotatableshaft so that the blade elements may be rotated about a horizontal axis.In testimony whereof I afiix my signature.

'6 TRIAN BERBECK.

